A catheter (CATH-uh-ter) is a thin, hollow tube that's inserted in the body, so it can deliver or carry away some substance. In cardiac catheterization (cath-uh-ter-eye-ZAY-shun), the tube is inserted through a blood vessel in the groin, and guided by x-ray to the heart.

It's known that high levels of blood cholesterol increase the risk of developing blocked arteries, which can lead to heart attack and stroke. Because of this, physicians routinely perform cholesterol tests, usually by drawing a sample of blood.

A colonoscopy (koe-lun-OSS-kuh-pee) is a test that uses a long, flexible instrument to examine the inside of the rectum and colon. This hollow device has a sensor at the end that relays images to a viewing screen.

A laparoscopy (lap-uh-ROSS-coe-pee) is a surgical procedure in which a small instrument is inserted through an incision in the navel. This instrument, called a laparoscope (LAP-uh-roe-scope), functions like a miniature telescope, with a light on the end, giving doctors an internal view of the abdominal cavity.

Mammography (mam-MAW-gruh-fee) is a special x-ray procedure used to detect breast cancer. The breast is lifted onto a shelf-like plate, then another plate is lowered to compress the tissue, so it can be photographed clearly.

There are two major types of pregnancy tests: those that use a urine sample, and those that require a blood sample. Urine pregnancy tests may be taken at a doctor's office, or home versions can be purchased at most drugstores.

X-ray imaging is used to view internal structures and organs. It's frequently used to examine bones, teeth, or breasts, or to diagnose tumors. A standard X-ray is produced by placing a particular part of the body before a sheet of film, then exposing that area to radiation from an X-ray tube.